Polydiacetylene conjugated polymer

Dobrosavljevic V, Stratt R (1987) Role of conformational disorder in the electronic-structure of conjugated polymers substituted polydiacetylenes. Phys Rev B 35 2781-2794... 

Conjugated polymers, in the undoped state, present remarkable nonlinear optical properties23. The material which has been most thoroughly investigated ever since 197624 is polydiacetylene para-toluene sulfonate (PTS). The polydiacetylene backbone consists of a... 

Fig. 15. Examples of conjugated polymers. The dotted lines indicate bonds lateral to the conjugated backbone. R and R2 denote end groups. The simplest conjugated polymer is polyene with alternating single and double bonds. By introducing triple bonds, one goes from polyene over polydiacetylene and polytriacetylene to polycarbyne. The aromatic polyphenylene and polyphenylenevinylene contain additional phenyl rings. Polythiophenes additionally possess sulfur atoms...

One approach to the determination of intrinsic properties, which has been utilized since the earliest interest in conjugated polymers, is to study the properties of related oligomers, as in the preceding paper ( ). It is, however, also possible to study model macromolecules, the polydiacetylene. The existence of solid state polymerization in diacetylene monomers has a long history (22, 23, 2 ), but it was not thoroughly studied until... 

The complex morphology of most conjugated polymers prevents direct measurement, and hinders understanding, of their intrinsic properties. Such problems do not occur for the polydiacetylenes, which can be prepared as macroscopic single crystals. Since polydiacetylenes can also be obtained in less perfect forms the effects of disorder can be studied. Spectroscopic techniques have been widely used to study the intrinsic properties of polydiacetylenes and their modification by disorder. The results obtained by optical and electron spin resonance spectroscopy are discussed. 

Conjugated polymers satisfy these requirements and have thus emerged as the most widely studied materials for their susceptability. Some of the examples of conjugated polymers, that have been studied for their third order NLO properties, are polydiacetylenes, poly-p-phenylenevinylenes and polythiophenes. However, CVD has only been used in the case of poly-p-phenylenevinylenes (PPV) [section 3.4], although values have not been reported. An excellent review of third order nonlinear optical properties of PPV in general, can be found in literature. Recently, McElvain et al. ° reported the values of CVD polyazomethines to be... 

Polydiacetylenes (PDAs) were the first class of conjugated polymer that could be produced in pure, single crystal form by the polymerization of the corresponding crystals of the monomeric dialkyne derivatives. DC measurements had demonstrated large electron mobilities in such PDA crystals. Because of this they were considered at the time to be of potential application as an organic semiconductor layer in electronic devices. While these hopes were unfulfilled, these... 

Some important aspects of topochemical polymerizations can be understood by inspection of Eq. (1), All reactivity comes about by very specific rotations of the monomers and by 1,4-addition of adjacent units and an extended, fully conjugated polymer chain is formed. The unique feature of the topochemical polymerization of diacetylenes is the fact that in many cases the reaction can be carried out as a single phase process. This leads to macroscopic, defect-free polymer single crystals which cannot be obtained, in principle, by crystallization of ready-made polymers by conventional methods. Thus, polydiacetylenes are ideal models for the investigation of the behaviour of macromolecules in their perfect three dimensional crystal lattice. 

Bloor, D. Experimental Studies of Polydiacetylenes Model Conjugated Polymers in Quantum Theory of Polymers , Springer Lecture Notes in Physics 113, 14 (1980)... 

Studies of nonlinear optical phenomena in conjugated polymers date back to the earliest studies of the polydiacetylenes [219], The large oscillator strength associated with the p-p transition gives rise to a relatively large linear electronic polarizibility. The early work speculated that because of the implied delocalization of charge in the excited state, conjugated polymers would offer opportunities as NLO materials. 

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